第一讲 嵌入式系统设计技术介绍.ppt

1、2020/7/16,嵌入式系统及应用Principles and Applications of the Embedded System,自动控制系 衣法臻 Tel: 51684087(O),2020/7/16,本课程是电子大类专业基础中的一门理论性、实践性和实用性都很强的课程，其任务是掌握嵌入式系统概念与原理、嵌入式实时操作系统原理、ARM处理器体系结构、ARM处理器指令系统与简单程序设计、ARM处理器结构与硬件原理，通过大量实验培养学生综合运用嵌入式系统解决实际问题的能力及实际动手的能力，让学生掌握嵌入式系统软件与硬件平台的建立，熟悉嵌入式系统的开发流程。,课程教学目标及学生应达到的能力,

2、2020/7/16,课程学时： 32 上课时间： 1-8 周 期末考试时间： 8周周末 成绩评定方法：开卷考试。考试成绩按百分制计算，考试 与平时的实验课完成情况及实验报告各占 50% 。,课时及成绩评定方法,2020/7/16,教 材：嵌入式系统，戴胜华，中国铁道出版社， 2008.5 参考书： 1. 周立功等，ARM DSP for signals 32-bit in IR port; 32-bit in Bluetooth 8-100 MB of memory All custom chips,2. Mobile Phones and Base Stations,Embedded sys

3、tems from real life,Massive signal processing Several processing tasks per connected call Based on DSPs Standard or custom 100s of processors,2020/7/16,User interface Embroidery patterns Touch-screen control ”Smart” Sets pressure of foot depending on task Raise foot when stopped New functions added

4、by upgrading the software,3. Sewing Machine,Embedded systems from real life,2020/7/16,嵌入式系统设计技术,Multiple networks Body, engine, telematics, media, safety,Multiple processors Up to 100 Networked together,4. Cars,Functions by embedded processing: ABS: Anti-lock braking systems ESP: Electronic stabilit

5、y control Airbags Efficient automatic gearboxes Theft prevention with smart keys Blind-angle alert systems . etc .,Large diversity in processor types: 8-bit door locks, lights, etc. 16-bit most functions 32-bit engine control, airbags,Embedded systems from real life,2020/7/16,Functions requiring com

6、puters: Radar Weapons Damage control Navigation basically everything Computers: Large servers 1000s of processors,5. Extremely Large,Embedded systems from real life,2020/7/16,Custom processors Graphics, sound 32-bit processors IR, Bluetooth Network, WLAN Harddisk RAID controllers 8-bit processors US

7、B Keyboard, mouse,6. Inside Your PC,Embedded systems from real life,2020/7/16,Growing importance of embedded systems,Growing economical importance of embedded systems: Worldwide mobile phone sales surpassed 156.4 mln units in Q2 2004, a 35% increase from Q2 2003. The worldwide portab

8、le flash player market exploded in 2003 and is expected to grow from 12.5 mln units in 2003 to over 50 mln units in 2008. Global 3G subscribers will grow from an estimated 45 mln at the end of 2004 to 85 mln in 2005. The number of broadband lines worldwide increased by almost 55% to over 123 mln in

9、the 12 months to the end of June 2004. Todays DVR (digital video recorders) users - 5% of households - will grow to 41% within five years. 79% of all high-end processors are used in embedded systems The future is embedded, Embedded is the future!,2020/7/16,Characteristics of Embedded Systems (1),Mus

10、t be dependable, Reliability R(t) = probability of system working correctly provided that is was working at t=0 Maintainability M(d) = probability of system working correctly d time units after error occurred. Availability A(t): probability of system working at time t Safety: no harm to be caused Se

11、curity: confidential and authentic communication Even perfectly designed systems can fail if the assumptions about the workload and possible errors turn out to be wrong.Making the system dependable must not be an after-thought, it must be considered from the very beginning,2020/7/16,Characteristics

12、of Embedded Systems (2),Must be efficient Energy efficient Code-size efficient(especially for systems on a chip) Run-time efficient Weight efficient Cost efficient Dedicated towards a certain applicationKnowledge about behavior at design time can be used to minimize resources and to maximize robustn

13、ess Dedicated user interface(no mouse, keyboard and screen) Hybrid systems (analog + digital parts).,2020/7/16,Characteristics of Embedded Systems (3),Many ES must meet real-time constraints A real-time system must react to stimuli from the controlled object (or the operator) within the time interva

14、l dictated by the environment. For real-time systems, right answers arriving too late are wrong. “A real-time constraint is called hard, if not meeting that constraint could result in a catastrophe” Kopetz, 1997. All other time-constraints are called soft. A guaranteed system response has to be expl

15、ained without statistical arguments Frequently connected to physical environment through sensors and actuators,2020/7/16,Characteristics of Embedded Systems (4),Typically, ES are reactive systems:A reactive system is one which is in continual interaction with is environment and executes at a pace de

16、termined by that environment“ Berg, 1995Behavior depends on input and current state. automata model appropriate, model of computable functions inappropriate.,Not every ES has all of the above characteristics. Def.: Information processing systems having most of the above characteristics are called em

17、bedded systems. Course on embedded systems makes sense because of the number of common characteristics.,2020/7/16,Quite a number of challenges, e.g. dependability,Dependability? Non-real time protocols used for real-time applications(e.g. Berlin fire department) Over-simplification of models(e.g. ai

18、rcraft anti-collision system) Using unsafe systems for safety-critical missions(e.g. voice control system in Los Angeles; 800planes without voice connection to tower for 3 hrs,2020/7/16,Challenges for implementation in hardware,Lack of flexibility (changing standards). Mask cost for specialized HW b

19、ecomes very expensive,Trend towards implementation in Software,2020/7/16,Software complexity is a challenge,Rob van Ommering, COPA Tutorial, as cited by: Gerrit Mller: Opportunities and challenges in embedded systems, Eindhoven Embedded Systems Institute, 2004,Exponential increase in software comple

20、xity In some areas code size is doubling every 9 months ST Microelectronics, Medea Workshop, Fall 2003 . 70% of the development cost for complex systems such as automotive electronics and communication systems are due to software developmentA. Sangiovanni-Vincentelli, 1999,2020/7/16,More challenges

21、for embedded software,Dynamic environments Capture the required behaviour! Validate specifications Efficient translation of specifications into implementations! How can we check that we meet real-time constraints? How do we validate embedded real-time software? (large volumes of data, testing may be

22、 safety-critical),2020/7/16,对计算机系统的回顾,2020/7/16, PC Laptop Mainframe -Server,桌面计算机范围,2020/7/16,体系结构之冯诺依曼结构,2020/7/16,体系结构之哈佛结构,2020/7/16,计算机的层次结构,2020/7/16,系统层次比较,2020/7/16,桌面系统的层次比较,2020/7/16,嵌入式系统的层次比较,2020/7/16,硬件构架桌面系统,2020/7/16,硬件构架嵌入式系统,2020/7/16,桌面机主板,2020/7/16,嵌入式系统主板,2020/7/16,对处理器的回顾,2020/

23、7/16,1971年，Intel Ted Hoff，4004,第一颗微处理器,2020/7/16,指令长度 4 8 16 32 64 集成度 微处理器 单片机 SOC,处理器分类（1）,2020/7/16, 用途 通用： X86、AMD、Cyrix、ARM、 MIPS、PowerPC等 专用： DSP、 指令集 RISC CISC：DSP,处理器分类（2）,2020/7/16,单板计算机(Microcontroller Unit, MCU) 嵌入式微处理器及其存储器、总线、外设等安装在一块电路板上，称为单板计算机。 STD-BUS、PC104等。 芯片内部集成ROM/EPROM、RAM、总线、

24、总线逻辑、定时/计数器、WatchDog、I/O、串行口、脉宽调制输出、A/D、D/A、Flash、RAM、EEPROM 等各种必要功能模块。 优点 体积小 功耗低 成本低 可靠性高,单板计算机,2020/7/16,SOC (System On Chip) 除个别无法集成的器件以外，整个嵌入式系统大部分均可集成到一块或几块芯片中。 Motorola 的M-Core，某些ARM 系列器件，Echelon 和Motorola 联合研制的Neuron 芯片 特点 体积小 功耗低 可靠性高,SOC（System On Chip）,2020/7/16,可以使用那些可编程设备 X86、PowerPC，AM

25、D 特点 内存可编程（Program memory） 通用的数据地址寄存器 通用的ALU 优点 开发迅速 低成本 高灵活性,微处理器（通用处理器）,2020/7/16,构架,2020/7/16,奔腾 II III 处理器结构,2020/7/16,用来执行单一特定程序 图形加速器、TCP卸载器、DSP 特点 构造简单，仅包含执行单一特定程序所需的 部件 没有编程内存（program memory） 优点 速度快 低功耗 尺寸小,微处理器（专用处理器）,2020/7/16,构架,2020/7/16,面向特定应用的优化的可编程处理器 有一般的特征 IOP、IXP 特点 可编程内存 数据路径优化 特殊

26、功能单元 优点 一定的灵活性 高性能,面向特定应用的处理器,2020/7/16,构架,2020/7/16,CISC：复杂指令集（Complex Instruction Set Computer） 具有大量的指令和寻址方式 8/2原则：80%的程序只使用20%的指令 大多数程序只使用少量的指令就能够运行。,指令集之复杂指令集,2020/7/16,RISC：精简指令集（Reduced Instruction Set Computer) 在通道中只包含最有用的指令 确保数据通道快速执行每一条指令 使CPU硬件结构设计变得更为简单,指令集之精简指令,2020/7/16,EPIC(Explicitly

27、Parallel Instruction Computing，显式 并行指令计算) 使用ILP（Instruction Level Parallelism）使编译器在程 序运行前便能找出其并行性，安排好指令执行的顺 序。 分支推断 风险装载 更加聪明的编译器,指令集之并行指令集,2020/7/16,超长指令字（VLIW）处理器 多发射机制 编译调度,指令集之超长指令,2020/7/16,指令系统设计： 决定于应用、性能、代码密度和方言的要求。 包括符号指令设计和编码设计。 指令的类型： 寻址方式：指令系统的重要特点。 与数据通路相关。 传输类指令：实现处理器内部存储之间以及与外部存储之间的数据

28、 传送。 与数据通路相关 运算类指令：实现指令描述的功能。 与ALU和其它运算部件相关 系统类指令：完成对系统资源的访问。 与操作系统的支持有关。,指令系统与处理器结构的关系,2020/7/16,指令的编码的相关因素：代码密度，功耗，译码器 指令编码与功耗； 连续执行的执行功耗取决于其引起的逻辑变化量 指令编码的海明距离，控制信号的海明距离 执行情况等，编译技术，OS，嵌入式应用,指令系统与处理器结构的关系,2020/7/16,历史上第一个真正的嵌入式系统是什么？ Apollo 导航计算机,嵌入式系统发展历史,2020/7/16,Hunter ICC 灌溉控制器 6,000 LOC (汇编语言

29、) 微内核(Hunter) 一个8-bit 微处理器 (8051) I2C网络 高可靠 小型嵌入式系统,嵌入式系统发展历史,2020/7/16,BMW 745i 2,000,000 LOC Windows CE OS 53个8-bit 嵌入式处理器 7个16-bit嵌入式处理器 1个32-bit嵌入式处理器 多种网络技术 大型嵌入式系统,嵌入式系统发展历史,2020/7/16,BMW 745 大型复杂的嵌入式系统可由若干个小型嵌入式系统组成,嵌入式系统发展历史,2020/7/16,根据IEEE（国际电气和电子工程师协会）的定义： 嵌入式系统是“用于控制、监视或者辅助操作机器和设备的装置”（原文

30、为devices used to control, monitor, or assist the operation of equipment, machinery or plants）。 可以看出此定义是从应用上考虑的，嵌入式系统是软件和硬件的综合体，还可以涵盖机电等附属装置。,什么是嵌入式系统？,2020/7/16,一般定义 “以应用为中心、以计算机技术为基础、软件硬件可裁剪、功能、可靠性、成本、体积、功耗严格要求的专用计算机系统。” 它主要由嵌入式微处理器、外围硬件设备、嵌入式操作系统以及用户应用软件等部分组成，用于实现对其它设备的控制监视和管理等功能。它通常嵌入在主要设备中运行。,什么是嵌入式系统？,2020/7/16,嵌入式系统的本质是把一个计算机系统嵌入到另一个对象体系中去。,什么是嵌入式系统？